Recent solid-state NMR studies have shown that the nuclear spin-lattice relaxation time of C60 is dominated by the chemical shift anisotropy relaxation mechanism. Those studies were performed at high magnetic field strengths and at temperatures not exceeding 320 K. We find that the spin-rotation relaxation mechanism contributes significantly to the total relaxation rate at low magnetic field strengths. This relaxation mechanism also becomes significantly at high temperatures for high magnetic field strengths. We find that the average value of the spin-rotation coupling constant is equal to 41 Hz.
Bibliographical noteFunding Information:
We appreciate experimehtal assistance from Joseph Vaughn and Burt Wolff. Important discussions with Mark S. Conradi (Washington University) and JoAnn Milliken (Naval Research Laboratory) are gratefully acknowledged. One of us (JHW) received postdoctoral support from the Na- tional High Magnetic Field Laboratory. One of us (TG) sincerely appreciates the assistance provided by Robert McKay, Greg Potter, and Jacob Schaefer (Washington University) and by Richard Rosanske (FSLJ) in construction of the 3.55 T spectrometer. One of us (TG) appreciates a COFRS Award provided by Florida State University. Acknowledgement is made to the Donors of The Petroleum Research Fund, administered by the American Chemical Society, for partial support of this research.